An Etymological Dictionary of the German Language/Annotated/Schreck
Schreck, masculine, ‘fright, terror, scare,’ from Middle High German schrëcke, masculine, allied to schrecken, verb, from Middle High German schrëcken, Old High German scrëcchôn, ‘to start up, spring up, spring, leap'; the early sense (compare the evolution in meaning of sich entsetzen) is preserved in the compound Heuschrecke. From this verb comes the causative schręcken, ‘to cause to spring up, terrify.’ In connection with the intensive form Old High German scrëcchón, compare further Old High German scricch, Middle High German schric(ck), masculine, ‘starting up suddenly, fright'; Dutch schrikken, ‘to frighten,’ Scandinavian skrika, ‘to glide.’ The root is essentially High German.